1. Field of the Invention
This invention relates in general to gas actuated valves and more particularly to the methods and devices to regulate the opening and closing of these gas actuated valves on gas well separators.
2. Background of the Invention
In the past, it has often been found useful to activate the opening and closing of valves by pressurized gas. For example, in gas well operations a source of pressurized gas is readily available to provide the power for automatic operation of devices in the area, including the operation of valves. Other suitable power sources are usually not conveniently available. In this gas well environment a particular valve which is usually gas actuated is the valve which regulates the flow of liquid from a liquid separator to a liquid holding tank. This liquid separator functions to remove water and hydrocarbon liquids from the gas before the gas is pumped away from the well. When the liquid level in the separator reaches a predetermined height, a float valve directs pressurized gas to a gas actuated valve on a dump line conduit which connects the bottom of the separator tank to a holding tank. The pressurized gas opens the valve and the pressure above the liquid in the separator causes the liquid to flow through the dump line into the holding tank until the liquid level in the separator falls to a second predetermined height. At this height the float valve causes the pressurized gas to be vented and when the pressure falls sufficiently the gas actuated valve closes. This ends the dump cycle and the liquid level in the separator again rises. Usually the dump line is buried to provide additional insulation and the lines above the ground are covered with insulation. Yet, even with these precautions, the dump line will occasionally freeze. This requires the dump line to be dug up and thawed during the cold months when the ground is frozen. Of course, digging under these conditions is extremely unpleasant and expensive.
One of the main reasons the liquid in the dump line freezes is that the operation of the gas actuated dump line valve is cyclical, causing liquid to be stagnant in the dump line for significant periods. However, it is not practical to provide a steady flow through the dump line and even if such steady flow were provided the line could still freeze.